In an electrolytic plant meant for electrolytically cleaning metals such as copper, zinc and nickel, there is typically a large number of electrolytic tanks that are in groups connected in series, so that the anode of the preceding tank is electrically connected to the cathode of the next tank by means of a highly electroconductive conductor rail that is placed on the wall between the tanks and is generally made of copper. This coupling is called a walker system. Said structure typically also includes a notched insulation rail placed on the conductor rail, which insulation rail separates the cathode of the preceding tank from the conductor rail of the anode of the next tank. Without said insulation, all electrodes of all tanks would be electrically connected, and current would not pass through the electrolyte.
The anodes and cathodes serving as electrodes are placed in an alternating fashion in the electrolytic tank. In order to perform the electrolytic cleaning in an advantageous way, the electrodes are placed as near to each other as possible, and consequently the mutual positioning of the electrodes must be carried out carefully in order to avoid short circuits. In connection with loading in the tank, separate loading elements approach the tank walls and the conductor rails resting on the tank together with their insulations, so that even small errors in the movements of a loading element may damage the tanks, the conductor rails or the insulations. Therefore the gripping spot of the electrodes should be such that the loading element could grip it as easily as possible, and that the chances for erroneous movements would be minimized.
A known way to arrange the distribution of electrodes in the tank is either to provide the electrode supporting elements with notching on the side by which they are placed on the conductor rail, or by notching the conductor rail so that the supporting elements supporting the electrode are set in notches provided for them. One possibility is to arrange the distribution of electrodes by notching the insulation rail provided in connection with the conductor rails. By notching the structures where the electrodes are hanging, it is also possible to prevent contacts between adjacent electrodes.
When electrodes are lifted from the tank in order to change their position, the electrodes are generally gripped at the notchings made underneath the support elements thereof, by means of the hooks of a transfer arrangement, such as a crane. Generally the support elements are also provided with separate transfer lugs that are gripped by the lifting hook of the transfer arrangement.
For instance from the U.S. Pat. No. 3,682,809 there is known a conductor rail arrangement where the conductor rail is uniform in structure, and the support elements supporting the electrodes are notched on the side where they are set on the conductor rails.
The prior art solutions have following drawbacks. The manufacturing of a notched conductor rail, generally extending over the whole tank, is expensive. On the other hand, if the employed rail is not notched, the electrodes are set in an inclined position owing to the insulation rail. Also the manufacturing of notched electrodes is expensive, and when immersing them in the tank, they must be lowered at exactly the right spot with respect to the conductor rail, when seen in the transversal direction of the tank. This requires extraordinary precision of the transfer operation. Owing to the notched insulation rail and possibly also owing to the conductor rail, the electrodes must be lowered in the tank at exactly the right spot with respect to the conductor rail, in order to make the electric contacts and separations to be correctly created. A possible heat extension of the conductor rail may cause problems while using an automatic crane, because when replacing electrodes, the heat extension of a conductor rail may shift the electrode positions, i.e. the notches. If a notched conductor rail is used, the electrode distribution cannot be changed without replacing all conductor rails and insulation rails. Because of the notched insulation rail, in practice the cleaning of the conductor rail always requires that the insulation rail is removed for the duration of the cleaning. This makes cleaning, particularly mechanized cleaning, more difficult. A notched rail must be made relatively thin, wherefore it generally becomes fairly weak and short-lived.